One of the main objectives of this research program is to develop and execute efficient synthesis of the following natural products: pretazettine, an Amaryllidaceae alkaloid that exhibits potent anticancer and antiviral activity; quadrone, a novel antineoplastic sesquiterpene isolated from the fermentation broth of Aspergillus terreus; verrucarol and anquidin (NSC-141537) which are trichothecane sesquiterpenes possessing anticancer activity; and taxusin, a taxane diterpene related to the anticancer agent taxol. Once the syntheses of these compounds are complete, reasonable quantities of them and/or closely related derivatives will be submitted to the National Cancer Institute for biological screening. Another important aspect of this program is the invention and development of new methods and strategies which will have general synthetic utility. One area of current interest is the development of procedures for the enantioselective construction of quaternary carbon atoms. Furthermore, efforts will be continued to explore the feasibility of employing intramolecular and bimolecular photochemical [2+2] cycloaddition reactions of enones and allylic alcohols with heteroatom-substituted alkenes as a key step in the syntheses of complex natural products. The title of this proposal has been changed to cover more adequately the substance of this research program, but it should be considered as a continuation of CA 21860.